Dolby's New Sound Tech Debuts in Pixar's Brave

Dolby’s newest cinema sound technology – unveiled with the 22 June U.S./Canadian release of Pixar’s new animated movie Brave – takes audiences into a more immersive experience by enabling precise placement of sound around the theater.

The technology, Atmos, improves upon the previous channel-based format by adding ceiling speakers; by enabling sound designers to pull single audio elements from the soundtrack and assign them to individual speakers; and by adding proprietary software that algorithmically adjusts the mix to theater size, configuration, and sound format.

It’s a system derived from five years of research done with input from entertainment industry sound experts. “This is not creating a technology and showing it to the industry after it’s done,” says Stuart Bowling, Dolby Laboratories’ senior worldwide technical marketing manager. “It’s the result of several years of research involving Dolby engineers sitting with sound mixers, designers, and directors, and asking them what they wished they could do.”

Traditional sound formats are recorded as a separate audio tracks for each channel, the channels go to one or multiple speaker cabinets, depending on the room configuration. Stereo is recorded on two channels. Dolby 5.1 uses five channels played back on three screen speakers and two groups of surround sound speakers on the sides and back of the theater, plus a discrete subwoofer. (Frequency-wise, a subwoofer is not regarded a full channel, hence the “.1”). Dolby 7.1 – the preceding industry leader unveiled with Pixar’s Toy Story 3 in 2010 - uses seven channels played back on three screen speakers and four groups of surround sound speakers (plus a subwoofer).

By comparison, Atmos offers the addition of ceiling speakers and the ability to project as many as 128 separate sound elements (called objects) to up to 64 individual speakers at a single time, rather than solely relying on seven individually recorded channels projected from as many groups of speakers, plus the subwoofer.

“It’s a hybrid system that’s taking the best of both worlds, by using channels and also placing pieces of sound in individual speakers and locations,” says Ramzi Haidamus, Dolby Laboratories’ executive vice president of sales and marketing, who likens the effect to a sonic version of 3D cinema.

More Emotional Impact

The difference means that an audience watching a character trapped in a basement, listening to footsteps walking across the ceiling, would also hear single footsteps advancing across the theater ceiling, one speaker at a time. Atmos could enhance a gunfight onscreen with the ping of bullets “hitting” individual speakers, as though the bullets were really whizzing through the theater. In the case of one scene in Brave, it more naturally articulates an ominous wind coursing through a castle by having it move around the theater, speaker by speaker.

“Since you can’t make the audience feel heat or cold, or smell the ocean, you use sounds to help provide the feeling you want the audience to have,” says Will Files, the re-recording mixer who oversaw the Atmos sound mix of Brave. “Take the concept of visual resolution – it’s the same idea with sound. Many more points of sound in a room create a higher resolution field that sounds more natural.”

It’s only recently that Dolby achieved the bandwidth, processing power, and proprietary algorithms to deliver this technology.

"Pixar called us, asking to push the sound for Toy Story 3 before we were ready to push it. So they released that in 7.1,” says Bowling. “But we brought them in to show them where the technology was going and got their feedback.” Atmos tools were still being tweaked when Brave embarked on its sound mix earlier this year, so the initial mix was in 7.1. “Their creative team came to Dolby before they started mixing Brave, set aside specific sound elements they wanted to place in individual speakers, and had them ready for when the Atmos technology got up to speed.” The final Atmos re-mix came in on 14 June four days before the world premiere.

Self-optimization

In addition to its immersive capabilities, the Atmos mix can reconfigure to any theater to provide a uniform sound experience, regardless of where one sits.

Currently, sound designers have to mix both Dolby 5.1 and 7.1 versions of a film’s soundtrack and deliver them to theaters with the corresponding sound systems. By comparison, a single Atmos mix contains metadata and positional data (where a sound objects need to be placed in space) that communicate with an Atmos server, housed in the projection room. That server contains information about the theater’s size, geometry, seating arrangement, and speaker placement, and “communicates” with the metadata to determine the best way to disperse the sound for that theater.

Given the US $25 000 – $30 000 cost to upgrade to Atmos, only 21 theaters around the world support it, including 15 in the U.S. and Canada, four in China, and one each in London and Barcelona. But over time, the system will makes its way into stadiums, convention halls, as well as computers, mobile platforms and games.

“The sound objects are infinitely scalable to any size room, because the math is based on vectors, as opposed to a finite number of sound channels, which distort with distance,” says Files. “To give a visual analogy, consider the difference between jpeg and pdf files. You can scale a pdf as far as you want and it looks great, but a jpeg only has a certain number of pixels. So Atmos is a technology that can grow into the foreseeable future.”

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